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A “built distribution” is what you’re probably used to thinking of either as a
“binary package” or an “installer” (depending on your background). It’s not
necessarily binary, though, because it might contain only Python source code
and/or byte-code; and we don’t call it a package, because that word is already
spoken for in Python. (And “installer” is a term specific to the world of
mainstream desktop systems.)

A built distribution is how you make life as easy as possible for installers of
your module distribution: for users of RPM-based Linux systems, it’s a binary
RPM; for Windows users, it’s an executable installer; for Debian-based Linux
users, it’s a Debian package; and so forth. Obviously, no one person will be
able to create built distributions for every platform under the sun, so the
Distutils are designed to enable module developers to concentrate on their
specialty—writing code and creating source distributions—while an
intermediary species called packagers springs up to turn source distributions
into built distributions for as many platforms as there are packagers.

Of course, the module developer could be his own packager; or the packager could
be a volunteer “out there” somewhere who has access to a platform which the
original developer does not; or it could be software periodically grabbing new
source distributions and turning them into built distributions for as many
platforms as the software has access to. Regardless of who they are, a packager
uses the setup script and the bdist command family to generate built
distributions.

As a simple example, if I run the following command in the Distutils source
tree:

pythonsetup.pybdist

then the Distutils builds my module distribution (the Distutils itself in this
case), does a “fake” installation (also in the build directory), and
creates the default type of built distribution for my platform. The default
format for built distributions is a “dumb” tar file on Unix, and a simple
executable installer on Windows. (That tar file is considered “dumb” because it
has to be unpacked in a specific location to work.)

Thus, the above command on a Unix system creates
Distutils-1.0.plat.tar.gz; unpacking this tarball from the right place
installs the Distutils just as though you had downloaded the source distribution
and run pythonsetup.pyinstall. (The “right place” is either the root of
the filesystem or Python’s prefix directory, depending on the options
given to the bdist_dumb command; the default is to make dumb
distributions relative to prefix.)

Obviously, for pure Python distributions, this isn’t any simpler than just
running pythonsetup.pyinstall—but for non-pure distributions, which
include extensions that would need to be compiled, it can mean the difference
between someone being able to use your extensions or not. And creating “smart”
built distributions, such as an RPM package or an executable installer for
Windows, is far more convenient for users even if your distribution doesn’t
include any extensions.

The bdist command has a --formats option, similar to the
sdist command, which you can use to select the types of built
distribution to generate: for example,

pythonsetup.pybdist--format=zip

would, when run on a Unix system, create Distutils-1.0.plat.zip—again, this archive would be unpacked from the root directory to install the
Distutils.

requires external rpm utility, version 3.0.4 or better (use rpm--version to find out which version you have)

You don’t have to use the bdist command with the --formats
option; you can also use the command that directly implements the format you’re
interested in. Some of these bdist “sub-commands” actually generate
several similar formats; for instance, the bdist_dumb command
generates all the “dumb” archive formats (tar, gztar, bztar,
xztar, ztar, and zip), and bdist_rpm generates both
binary and source RPMs. The bdist sub-commands, and the formats
generated by each, are:

Command

Formats

bdist_dumb

tar, gztar, bztar, xztar, ztar, zip

bdist_rpm

rpm, srpm

bdist_wininst

wininst

bdist_msi

msi

The following sections give details on the individual bdist_*
commands.

The RPM format is used by many popular Linux distributions, including Red Hat,
SuSE, and Mandrake. If one of these (or any of the other RPM-based Linux
distributions) is your usual environment, creating RPM packages for other users
of that same distribution is trivial. Depending on the complexity of your module
distribution and differences between Linux distributions, you may also be able
to create RPMs that work on different RPM-based distributions.

The usual way to create an RPM of your module distribution is to run the
bdist_rpm command:

pythonsetup.pybdist_rpm

or the bdist command with the --format option:

pythonsetup.pybdist--formats=rpm

The former allows you to specify RPM-specific options; the latter allows you to
easily specify multiple formats in one run. If you need to do both, you can
explicitly specify multiple bdist_* commands and their options:

Creating RPM packages is driven by a .spec file, much as using the
Distutils is driven by the setup script. To make your life easier, the
bdist_rpm command normally creates a .spec file based on the
information you supply in the setup script, on the command line, and in any
Distutils configuration files. Various options and sections in the
.spec file are derived from options in the setup script as follows:

RPM .spec file option or section

Distutils setup script option

Name

name

Summary (in preamble)

description

Version

version

Vendor

author and author_email,
or — & maintainer and
maintainer_email

Copyright

license

Url

url

%description (section)

long_description

Additionally, there are many options in .spec files that don’t have
corresponding options in the setup script. Most of these are handled through
options to the bdist_rpm command as follows:

RPM .spec file option
or section

bdist_rpm option

default value

Release

release

“1”

Group

group

“Development/Libraries”

Vendor

vendor

(see above)

Packager

packager

(none)

Provides

provides

(none)

Requires

requires

(none)

Conflicts

conflicts

(none)

Obsoletes

obsoletes

(none)

Distribution

distribution_name

(none)

BuildRequires

build_requires

(none)

Icon

icon

(none)

Obviously, supplying even a few of these options on the command-line would be
tedious and error-prone, so it’s usually best to put them in the setup
configuration file, setup.cfg—see section Writing the Setup Configuration File. If
you distribute or package many Python module distributions, you might want to
put options that apply to all of them in your personal Distutils configuration
file (~/.pydistutils.cfg). If you want to temporarily disable
this file, you can pass the --no-user-cfg option to setup.py.

There are three steps to building a binary RPM package, all of which are
handled automatically by the Distutils:

create a .spec file, which describes the package (analogous to the
Distutils setup script; in fact, much of the information in the setup script
winds up in the .spec file)

Normally, RPM bundles the last two steps together; when you use the Distutils,
all three steps are typically bundled together.

If you wish, you can separate these three steps. You can use the
--spec-only option to make bdist_rpm just create the
.spec file and exit; in this case, the .spec file will be
written to the “distribution directory”—normally dist/, but
customizable with the --dist-dir option. (Normally, the .spec
file winds up deep in the “build tree,” in a temporary directory created by
bdist_rpm.)

Executable installers are the natural format for binary distributions on
Windows. They display a nice graphical user interface, display some information
about the module distribution to be installed taken from the metadata in the
setup script, let the user select a few options, and start or cancel the
installation.

Since the metadata is taken from the setup script, creating Windows installers
is usually as easy as running:

pythonsetup.pybdist_wininst

or the bdist command with the --formats option:

pythonsetup.pybdist--formats=wininst

If you have a pure module distribution (only containing pure Python modules and
packages), the resulting installer will be version independent and have a name
like foo-1.0.win32.exe. These installers can even be created on Unix
platforms or Mac OS X.

If you have a non-pure distribution, the extensions can only be created on a
Windows platform, and will be Python version dependent. The installer filename
will reflect this and now has the form foo-1.0.win32-py2.0.exe. You
have to create a separate installer for every Python version you want to
support.

The installer will try to compile pure modules into bytecode after installation
on the target system in normal and optimizing mode. If you don’t want this to
happen for some reason, you can run the bdist_wininst command with
the --no-target-compile and/or the --no-target-optimize
option.

By default the installer will display the cool “Python Powered” logo when it is
run, but you can also supply your own 152x261 bitmap which must be a Windows
.bmp file with the --bitmap option.

The installer will also display a large title on the desktop background window
when it is run, which is constructed from the name of your distribution and the
version number. This can be changed to another text by using the
--title option.

The installer file will be written to the “distribution directory” — normally
dist/, but customizable with the --dist-dir option.

Starting with Python 2.6, distutils is capable of cross-compiling between
Windows platforms. In practice, this means that with the correct tools
installed, you can use a 32bit version of Windows to create 64bit extensions
and vice-versa.

To build for an alternate platform, specify the --plat-name option
to the build command. Valid values are currently ‘win32’, ‘win-amd64’ and
‘win-ia64’. For example, on a 32bit version of Windows, you could execute:

pythonsetup.pybuild--plat-name=win-amd64

to build a 64bit version of your extension. The Windows Installers also
support this option, so the command:

pythonsetup.pybuild--plat-name=win-amd64bdist_wininst

would create a 64bit installation executable on your 32bit version of Windows.

To cross-compile, you must download the Python source code and cross-compile
Python itself for the platform you are targeting - it is not possible from a
binary installation of Python (as the .lib etc file for other platforms are
not included.) In practice, this means the user of a 32 bit operating
system will need to use Visual Studio 2008 to open the
PCBuild/PCbuild.sln solution in the Python source tree and build the
“x64” configuration of the ‘pythoncore’ project before cross-compiling
extensions is possible.

Note that by default, Visual Studio 2008 does not install 64bit compilers or
tools. You may need to reexecute the Visual Studio setup process and select
these tools (using Control Panel->[Add/Remove] Programs is a convenient way to
check or modify your existing install.)

Starting with Python 2.3, a postinstallation script can be specified with the
--install-script option. The basename of the script must be
specified, and the script filename must also be listed in the scripts argument
to the setup function.

This script will be run at installation time on the target system after all the
files have been copied, with argv[1] set to -install, and again at
uninstallation time before the files are removed with argv[1] set to
-remove.

The installation script runs embedded in the windows installer, every output
(sys.stdout, sys.stderr) is redirected into a buffer and will be
displayed in the GUI after the script has finished.

Some functions especially useful in this context are available as additional
built-in functions in the installation script.

These functions should be called when a directory or file is created by the
postinstall script at installation time. It will register path with the
uninstaller, so that it will be removed when the distribution is uninstalled.
To be safe, directories are only removed if they are empty.

This function creates a shortcut. target is the path to the program to be
started by the shortcut. description is the description of the shortcut.
filename is the title of the shortcut that the user will see. arguments
specifies the command line arguments, if any. workdir is the working directory
for the program. iconpath is the file containing the icon for the shortcut,
and iconindex is the index of the icon in the file iconpath. Again, for
details consult the Microsoft documentation for the IShellLink
interface.

Starting with Python 2.6, bdist_wininst supports a --user-access-control
option. The default is ‘none’ (meaning no UAC handling is done), and other
valid values are ‘auto’ (meaning prompt for UAC elevation if Python was
installed for all users) and ‘force’ (meaning always prompt for elevation).